Citrus are acidic fruits; typically juicy, always nutritious. All share a commonality of tangy flavor and sweet-sour aroma.
Citrus are especially high in vitamin C. They also provide B vitamins, dietary fiber, potassium, calcium, phosphorus, magnesium, copper, and various phytonutrients.
The origin of citrus remains unresolved, but indications are tropical Southeast Asia or Australasia. The earliest reference to citrus is in 2200 bce Chinese texts.
Mandarin and sweet oranges originated in China. Lemons were first grown in India. After citrons and lemons made their way to the Mediterranean during Roman times, their rarity made them status symbols among the elite.
Because citrus trees easily hybridize via grafting, there are innumerable citrus fruits. Major varieties include citron, grapefruit, kumquat, lemon, lime, orange, tangelo, and tangerine.